I've read David Benator's book "Better never to have been born: the harm of coming into existence" and no one has ever refuted his key arguments to my satisfaction. I am going to explain the main thrust of his arguments to you and then invite you to share your reactions to it.

His argument is simple but, to my mind, devastatingly persuasive. He states that if you are born you experience both good (positive mental states) and bad (negative mental states) during the course of your life. If, however, one is never born then one won't experience any bad (pain, anxiety, existential angst etc). This is a good thing obviously. Of course, if one is never born one never experiences any positive mental states either (joy, love, sexual satisfaction etc). However, if there is nobody to experience these positive mental states I challenge any poster here to suggest how this can be a deprivation FOR THE PERSON WHO NEVER CAME INTO EXISTENCE.

So let's look at the following analysis of therelative merits of being born as opposed to the relative merits of not being born:

Scenario A: You are born. You experience both pleasure and pain throughout your life. You die. Pleasure experienced? Yes. Pain experienced? Yes.

What can we say about this? We can say that being born was partly a good thing for the individual due to the pleasure experienced in his/her life (+1) and we can say that being born was also partly negative for that person because of the pain they experienced (-1) during the course of their life. So we have a (+1) and a (-1) for being born.

Now let's look at scenario B: You are not born. You never come into existence. End of story. Pleasure experienced? No. Pain experienced? No.

What can we possibly say about or on behalf of this non-existent person? Well, we can say that he/she never experienced (or will experience) any positive mental states. That's surely a bad thing, right? WRONG, WRONG, WRONG! Existence precedes essence. If there is no person to experience any deprivation of positive mental states how can we possibly say that a'non-person' has been deprived or robbed in any way by not having been brought into existence? I don't think we can.

As a result of this it would be wholly inaccurate to describe the non-existence of a person as a negative thing for the non-existent person in terms of not experiencing the good things in life. Sure we can most assuredly state that being a non-existent person is not a positive thing either in terms of not being able to experience positive mental states - an obvious outcome of their not being born. However, this does not give us licence to make the opposite claim either - that somehow not being born causes a harm to the person who was not born as they would miss out on the positive things that life can potentially offer. Clearly then not being born is neither a positive nor negative thing in terms of the inability to experience pleasure. It is clearly neutral.

Now let's look at the pain that a non-existent person avoids by not being born. He never comes into existence so he never experiences any pain. That is a good thing!(+1) But wait, I can hear you forming objections to this even as I type. Surely, you may object, if nobody is born how can the lack of experienced pain be a good thing as there would be nobody to experience the total lack of pain. Well...simply because of the fact that we can legitimately compare the suffering a person experiences in his life with the lack of pain he would have experienced if he had never been born in the first place to experience that pain. We can make that comparison I assure you. We can always say to somebody who was born: "I'm going to make you rue the day that your father ever laid eyes on your mother" shortly before torturing them to death. But we cannot say to a non-existent person (or anything else for that matter): "Suffer, non-existent person, suffer! Experience the deprivation of pleasure and weep for the lost opportunity you had to experience the wonder that life would have had in store for you if you had only been born."

However pleasure and pain are subjective. Some people are happier and other are unhappy. Some people have more positive points than negative in their lives while others have more negatives than positives.
However the purpose of the anti-birth is to avoid damages to people whose lives would have more negatives than positives. Morally speaking, prevent damage or injury to someone is more important than benefit a person. Pontential humans whose lives would be a happy experience would not be harmed because the state or non-state of inexistence there is no deprivation of happiness and absence from pain and suffering in the lives of people whose lives would be miserable is a good thing because no pain is preferable the presence of the same.
In this sense procreation should be avoided in order not to harm the people whose lives would be a sad experience even if these people were still a minority.